Method and device for instrument, bone segment, tissue and organ navigation

ABSTRACT

The invention relates to a method and a device for instrument, bone segment, tissue and organ navigation. The general problem covered by the invention relates to referencing between a data set (that geometrically describes the spatial model of a body) and the real physical environment in which said body is located. For referencing, a three-dimensional position reference body is used or placed in the real body, said position reference body consisting of one or more elementary bodies (markers) that can be spatially and sensorially detected and defining a fixed geometric reference with respect to the center of gravity of the body or the other reference volumes of the body. A correlation of the position reference body or its elementary body is performed in the data model and in the physical world for registration.

[0001] The invention relates to a method and a device according to thepreamble of claim 1 and 3.

[0002] A patient data set and an operating site during surgery aretypically referenced to each other by using either anatomical indiciaor—before an image data set is created—implants (bone or skin markers)that are applied to the patient. The implants are indicatedsimultaneously with an input device at a workstation and with alocalization system on the patient.

[0003] A more general task relates to referencing between a data set(which describes geometrically the spatial model of a body) and the realphysical environment in which the actual body is placed. Forreferencing, a three-dimensional position reference body is used on orapplied to the real body. The position reference body consists of one ormore elementary bodies (markers) whose 3-dimensional position can bedetected with sensors and which define a fixed geometric reference withrespect to the center of gravity of the body or to other referencevolumes of the body. For the purpose of registration, the positionreference body and/or its elementary bodies are correlated in the datamodel and in the physical world.

[0004] Unlike the present method, the German patent DE 197 47 427describes a method and a device wherein the characteristic surface ofbone structures is used for providing a reference between a data set andthe operating site. DE 197 47 427 describes an individual template whichcarries 3-D localization markers and is applied to and/or screwed on abone segment.

[0005] The method has the disadvantage that an expensive CAD-CAM modelhas to be produced from a patient data set before an individual templatecan be manufactured. With many surgical procedures, large areas of bonehave to be exposed for applying the individual surface template, whichmakes the procedure unnecessarily invasive.

[0006] It is an object of the present invention to provide a method anda device for instrument, bone segment, tissue and organ navigation,which operates without auxiliary devices, such as templates, andfacilitates a safe and reproducible navigation.

[0007] This object is solved by the characterizing features of claim 1and 3.

[0008] By using optical measurements and by referencing the operatingsite via the characteristic surface of a soft tissue envelope or a bonesurface, the cost can be reduced significantly and the surgical accesspath can be significantly less invasive. For a bone segment navigationwith the present invention, the 3-D localization markers can beindividually secured on a bone segment independent of a template—such asa screw, which opens additional possibilities for a minimally-invasivesurgical procedure.

[0009] Optical referencing between the data set, the operating site andthe 3-D localization markers is also faster and more precise than theaforedescribed referencing method that uses anatomical indicia andimplants, because large surface structures in a patient data set (forexample MRT or CT) can be imaged more exactly and reproduced than small,singular reference points.

[0010] Embodiments of the invention are illustrated in the drawings andwill be described hereinafter in more detail.

[0011] It is shown in

[0012]FIG. 1 a schematic diagram of the devices in an operating room,

[0013]FIG. 2 a detailed view of the 3-D reference markers with a devicefor detecting these markers by optical methods using 3-D scanners,

[0014]FIG. 3 a geometric device for optical detection of 3-D referencemarkers, which are affixed to a frame,

[0015]FIG. 4 a perspective view of the 3-D reference markers withassociated geometric devices of different form (depression/sulcus,raised portion/crista, planar color-coded surface) for optical detectionwith the 3-D scanner,

[0016]FIG. 5 alternative examples of different geometric forms that havea known spatial association with the 3-D marker,

[0017]FIG. 6 additional coupled referencing markers,

[0018]FIG. 7 an embodiment with a different coupling between the scannerand position detection unit,

[0019]FIG. 8 referencing of bodies that do not necessarily have a stableform, and

[0020]FIG. 9 device for positioning bodies that do not necessarily havea stable form.

[0021] The invention will be described hereinafter in more detail withreference to a first embodiment. The entire system 1 is used for opticalreferencing between an operating site, a patient data set and 3-Dmarkers.

[0022] An optical 3-D scanner 5 is attached to a position detection unit4 via a coupling device 13. The position detection unit 4 can acquire,for example, infrared signals, ultrasound signals or electromagneticsignals and allows the determination of three-dimensional coordinates ofa corresponding 3-D marker 6 (for example: ultrasound transmitter,infrared transmitter, electromagnetic transmitter and/or reflectors 17for all types of waves, ultrasound, infrared, radar, etc.). The 3-Dscanner 5 (for example a 3-D laser scanner 5 or a radar unit 5 a) candetect the shape and color of surfaces (for example 7), but not thesignals from the 3-D markers 6. The signals from the 3-D markers 6 canbe transmitted actively, for example with an LED, or passively, forexample by using reflectors.

[0023] The data measured by the position detection unit 4 and the 3-Dscanner 5 or the radar unit 5 a are transmitted via a connection 10 and11 to a display and processing unit 2. Since the position detection unit4 and the 3-D scanner 5 are coupled via a connection 13 having a knowngeometrical relationship and/or are kinematically attached to each othervia a connection 13, all coordinates measured with the positiondetection unit 4 can also be expressed in the coordinate system of the3-D scanner 5 and vice versa.

[0024] A planning unit 3 is connected via 12 to the display andprocessing unit 2. Surgical procedures can be simulated on this planningunit 3; for example, resetting osteotomies can be planned before a bonesegment navigation.

[0025] In this embodiment, at least three 3-D markers 6 are attached tothe patient, which define a coordinate system on the patient. GeometricFIGS. 7 which can be detetced by the 3-D scanner 5, are arranged in aknown, fixed spatial relationship to these 3-D markers 6. These FIGS. 7can be implemented, for example, as a depression/sulcus 7 a, a raisedportion/crista 7 b, as color-coded lines and fields 7 c or as a barcode. The geometric FIG. 7 can also be in the form of a base on which a3-D marker 6 is placed. The geometric FIG. 7 can also be formed directlyby one or several 3-D markers 6.

[0026] The coordinates of the 3-D markers 6 can be uniquely determinedby processing unit 2 from the geometry of the devices 7 by an inversetransformation. The geometry of these devices 7 can be different (7′,7″, 7′″); it is only necessary that the geometry can be detected by the3-D scanner 5 and that the processing unit 2 can determine thecoordinates of the 3-D markers 6 from the geometry of the devices 7.

[0027] If the three 3-D markers 6 are fixedly connected with one anotherby a frame 14 in order to define a patient coordinate system, then thecoordinates of the 3-D markers 6 can be determined by the processingunit 2 from the arrangement of the geometric FIGS. 7 on the frame 14.Alternatively, the scanner can also determine the coordinates directlyby the analyzing the known geometries of the 3-D markers.

[0028] The operating site, the patient data set and the 3-D markers 6are referenced to each other by first detecting with the 3-D scanner 5the soft tissue (before the surgery, i.e., before the soft tissue swellsor is displaced) or the bone surfaces 9 of the patient. The processingunit 2 processes the data from the 3-D scanner 5 and determines the mostadvantageous surface area fit between the patient and the patient dataset. Thereafter, the patient and the patient data set can be referencedto each other by a coordinate transformation.

[0029] So far, however, the 3-D scanner 5 has not yet detected the 3-Dmarkers 6. However, since the geometric devices 7 surrounding the 3-Dmarkers 6 were scanned together with the patient and since the spatialrelationship between the 3-D markers 6 and the geometric devices 7 isknown, the coordinates of the 3-D markers 6 can be imaged both in thecoordinate system of the data supplied by the 3-D scanner 5 as well asin the coordinate system of the patient data set.

[0030] Additional 3-D markers 8 which are either attached directly on abone segment 9 or on a work tool 15 or coupled to these through akinematic measurement mechanism or a coordinate measurement device, cansubsequently be imaged in the patient data set on the display andprocessing unit 2.

[0031] In this way, a spatial displacement of a bone segment 9 that hasbeen simulated on the planning unit 3, can also be reproduced on thepatient.

[0032] Instead of coupling the 3-D scanner 5 and the 3-D marker positiondetection unit 4 through a fixed connection, the 3-D scanner 5 can alsobe flexibly coupled to the position detection unit 4 so as to be movablerelative to the 3-D marker position detection unit 4, and can itself beprovided with 3-D markers 8 for detection by the 3-D marker positiondetection unit 4.

[0033]FIG. 6 shows a 3-D marker 16 embodied as an LED and embodied as apassive reflector 17. The 3-D geometry of the bodies is sufficientlyknown and can therefore be used directly to uniquely determine thecoordinates of the markers from the scanner data, without the need foradditional encoding. The markers can be directly used as devicegeometries.

[0034]FIG. 7 shows an embodiment of a scanner 18 with a kinematiccoordinate measurement device implemented as a measuring profile 19 anddirectly connected with the position detection unit. If necessary, therelative position of the scanner 18 can be determined by the secondkinematic coordinate measurement device with significantly higheraccuracy and measuring frequency. In an alternate embodiment, the baseof the kinematic coordinate measurement device itself can be providedwith a position reference body 20. In the simplest case, the kinematiccoordinate measurement device is a simple body (for example a rod) ofknown geometry. Advantageously, the kinematic coordinate measurementdevice can also be attached to a table or applied directly on thepatient, depending of which relative accuracy between the markers andthe body should be optimized.

[0035]FIG. 8 shows instead of a bone (hard tissue) a more typicalsituation involving tissue that does not necessarily have a stable form,and/or an arbitrary body 21. In the simplest case, a relationship isestablished via a center of a gravity 22 of the body or anotherreference volume 23. This is advantageous when the method is to beapplied also to soft tissue, organs or implants during alignment,transplantation and implementation. Even if perfect dimensionalstability is not achieved, the method and device can still assist withnavigation. Elementary bodies 24 are arranged on the position referencebody 20 a.

[0036]FIG. 9 shows a device for affixing the position reference bodies20 b to bodies 21 that may lack dimensional stability. The positionreference body 20 b is hereby attached to a mechanism that is disposedon the body 21 that lacks dimensional stability. In the depictedexample, body tissue is drawn in by a reduced pressure process through alumen 25 and through a membrane 26 and pressed into a predefined form.This form can advantageously have a shape that facilitates, for example,placement during transplantation or implantation. Other methods foraffixing the tissue to the device, for example with adhesive, burrs orstitches, are also feasible.

1. Method for instrument and bone segment as well as tissue and organnavigation, wherein position data of position reference bodies arrangedon bones, tissue or organs and contour data and/or surface data ofgeometric figures arranged on or spatially correlated with the positionreference bodies are detected and wherein the data are mathematicallyprocessed in such a way that the position data and the contour and/orsurface data can be represented in a common coordinate system.
 2. Methodaccording to claim 1, characterized in that the position referencebodies define a fixed geometric reference relative to the center ofgravity of the body or other body reference volumes and that for thepurpose of registration, the position reference body or its elementarybodies are associated with each other in the data model and in thephysical world.
 3. Device for instrument and bone segment as well astissue and organ navigation, characterized in that a 3-D marker positiondetection unit (4) for detecting signals from 3-D markers is coupled toan optical 3-D scanner (5) or radar unit (5 a) for detecting surfacesand that geometric figures (7) are connected with the 3-D markers (6) orone or several markers (6) are shaped as geometric figures (7) that canbe detected by the 3-D scanner (5), thereby allowing a determination ofthe coordinates of the 3-D markers (6) on the display and processingunit (2).
 4. Device according to claim 3, characterized in that thedisplay and processing unit (2) enables referencing between an operatingsite and a patient data set through a computational surface fit andenables referencing between the data of the 3-D position detection unit(4) and the data of the 3-D scanner (5) with the help of geometricdevices (7) disposed on the 3-D markers (6).
 5. Device according toclaim 3, characterized in that during/before/after referencing betweenthe operating site, the patient data set and the 3-D markers (6),additional 3-D markers (8) are applied on a bone segment (9) of thepatient or on an instrument (15) for the purpose of enabling a bonesegment navigation or instrument navigation.
 6. Device according toclaim 3, characterized in that geometric figures (7) are applied to oron the frame (14) of 3-D markers (6) that are connected with each other.7. Device according to claim 3, characterized in that a base, on which a3-D marker (6) is placed, is provided as a geometric figure (7) fordetermining the coordinates of the 3-D markers on the display andprocessing unit (2) from the 3-D scanner (5) measurement data.
 8. Deviceaccording to claim 3, characterized in that the frame (14) of 3-Dmarkers (6) that are connected with each other, forms the geometricfigure (7) for determining the coordinates of the 3-D markers on thedisplay and processing unit (2) from the 3-D scanner (5) measurementdata.
 9. Device according to claim 3, characterized in that thatgeometric figures (7) that can be detected by the 3-D scanner (5) areformed as a recess/sulcus (7 a) or as a raised portion/crista (7 b) oras a sphere.
 10. Device according to claim 3, characterized in that thegeometric figures (7) that can be detected by the 3-D scanner, arecolor-coded or formed as a bar code.
 11. Devices according to claim 3,characterized in that different geometric figures (7′, 7″, 7′″) that canbe detected by the 3-D scanner (5), are connected with 3-D markers (6).12. Devices according to claim 3, characterized in that the couplingbetween the 3-D marker position detection unit (4) and the 3-D scanner(5) or the radar unit (5 a) is a fixed connection.
 13. Devices accordingto claim 3, characterized in that the coupling between the 3-D markerposition detection unit (4) and the 3-D scanner (5) or the radar unit (5a) is a connection via a coordinate measuring arm (19).
 14. Deviceaccording to claim 3, characterized in that the 3-D scanner (5) is notrigidly coupled with the position detection unit (4), but remain mobilewith respect to the 3-D marker position detection unit (4) and is itselfprovided with 3-D markers (8) so as to be able to be registered by the3-D marker position detection unit (4).
 15. Device according to claim14, characterized in that the 3-D scanner is implemented as a hand-held3-D scanner.
 16. Device according to claim 3, characterized in that the3-D scanner (5) and the position detection unit (4) use the samereceiver components for detecting the position information and the 3-Dinformation.
 17. Device according to claim 16, characterized in that the3-D scanner (5) and the position detection unit (4) use the sametransmitter components for detecting the position information and the3-D information and/or process the same physical transmitter waves.